Field of the Invention
The present invention generally relates to dual band directional antennas. The present invention more specifically relates to reflector switching between high-band and low-band patterns.
Description of the Related Art
Antennas that provide dual band coverage (for example, 2.4 GHz and 5.0 GHz) with a single feed are common. Attempting to form a directional pattern in one of the frequency bands using commonly available antennas with reflecting parasitic elements, however, will often cause unwanted changes in the patterns of the other band. Such changes complicate simultaneous operation in both frequency bands.
More specifically, changes in lower frequency band reflectors are prone to affect patterns in the higher frequency band patterns. Changes in the high frequency band reflectors typically will not affect low frequency band patterns because high frequency band reflectors are shorter with respect to the low-band wavelength. As a result, the band patterns of the lower frequencies are not affected. This is true, however, only when the frequency ratio between the high frequency band and low frequency band is sufficiently large (e.g., a frequency ratio of 2:1 or greater). When the frequency ratio between the high frequency band and low frequency band is not large enough (e.g., less than 2:1), the high frequency band may interfere with low frequency band operations.
There is a need in the art for dual band directional antennas that allow for simultaneous operation in high and low frequency bands. More specifically, there is a need for dual band directional antennas with low frequency band reflectors that form desired patterns in low frequency while remaining transparent to high frequency bands such that patterns in the high frequency are not otherwise adversely affected.